Apparatus and method for characterizing libraries of different materials using X-ray scattering

ABSTRACT

An apparatus for characterizing a library is provided in which the library contains an array of elements and each element contains a different combination of materials. The apparatus includes an x-ray beam directed at the library, a chamber which houses the library and a beamline for directing the x-ray beam onto the library in the chamber. The chamber may include a translation stage that holds the library and that is programmable to change the position of the library relative to the x-ray beam and a controller that controls the movement of the translation stage to expose an element to the x-ray beam in order to rapidly characterize the element in the library. During the characterization, the x-ray beam scatters off of the element and a detector detects the scattered x-ray beam in order to generate characterization data for the element.

This application is a continuation of application Ser. No. 09/215,417filed Dec. 18, 1998 abandoned.

BACKGROUND OF THE INVENTION

This invention relates generally to an apparatus and method for rapidlydetermining the characteristics of an array of diverse materials whichhave been created on a surface of a substrate, and in particular, to anapparatus and method for rapidly determining the characteristics of alibrary of diverse materials using high energy electromagneticradiation.

Combinatorial material science refers generally to methods for creatinga collection of chemically diverse compounds or materials and to methodsfor rapidly testing or screening this library of compounds or materialsfor desirable characteristics or properties. The combinatorialtechnique, which was introduced to the pharmaceutical industry in thelate 1980s, has dramatically sped up the drug discovery process.Recently, combinatorial techniques have been applied to the synthesis ofinorganic materials. Using various surface deposition techniques,masking strategies or processing conditions, it is possible to generatehundreds or thousands of materials with distinct compositions per squareinch in an array of elements which form a library. The materialsgenerated using these combinatorial techniques have included hightemperature superconductors, magnetoresistors, phosphors and pigments.The discovery of new catalysts should also benefit from thesecombinatorial techniques. General combinatorial material sciencemethodologies are disclosed, for example, in U.S. Pat. No. 5,776,359which is incorporated herein by reference.

The problem is that, although these libraries of hundreds or thousandsof new potential materials have been generated, these libraries need tobe screened for performance characteristics or properties andconventional screening techniques are not sufficiently fast. Anotherproblem for conventional characterization techniques is the lowconcentration of components in each element of the library. It istherefore necessary to be able to accurately measure these lowconcentration levels.

In general, x-ray scattering is a well known characterization technique.In addition, the various pieces of an x-ray scattering apparatus arewell known. For example, U.S. Pat. Nos. 5,757,882, 5,646,976 and 5163078describe a multilayer mirror being used in an x-ray beamline. The use offlat glass mirrors for x-ray optics is disclosed in Franks, A., BritishJournal of Applied Physics., Volume 9, page 349 (1958) and Milch, J. R.,Journal of Applied Cryst., Volume 16, page 198 (1983). X-ray beamlineswith rotating anode sources and two flat glass mirrors are disclosed inMilch, J. R., Journal of Applied Cryst., Volume 16, page 198 (1983) andHajduk, D. A., Morphological Transitions in Block Copolymers, Ph.D.dissertation, Princeton University (1994). In addition, x-ray detectors,such as multiwire area detectors (See U.S. Pat. Nos. 3,911,279 and4,076,981) and CCD-based detectors with integral memories (See U.S. Pat.No. 5,629,524) are known. Many x-ray detectors have also been describedin various journals and other publications including Gruner, S. M.,Curr. Op. Struct. Biol. 1994, 4, 765; Gruner, S. M., Rev. Sci. Inst.1989, 60, 1545; Ilinson, N. M., Nucl. Inst. Methods Phys. Res. 1989,A275,587; and Eikenberry E. F. et al., “X-Ray Detectors: Comparison ofFilm, Storage Phosphors and CCD Detectors” in Morgan, ed. PhotoelectricImage Devices Bristol: Inst. of Physics Conf. Ser. No. 121, Institute ofPhysics 1992, 273.

One conventional technique for structural characterization is x-rayscattering. In this technique, a monochromatic, collimated x-ray beamilluminates a material of interest, and the spatial distribution of thescattered radiation is analyzed to provide information on the structure,dimensions, and degree of ordering of the specimen. Low concentrationsof strongly scattering constituent atoms or substructures may also bedetected and quantified by this technique. Similar results may beobtained by analyzing the distribution of photon energies scattered intoa fixed region of space from a polychromatic x-ray beam. Although thelow photon flux and brilliance characteristic of commercially availableinstruments is acceptable for measurements of individual samples, it isof limited value for combinatorial materials science work. Typicalmeasurements on conventional sources require at least fifteen minutesper specimen, implying at least 24 hours to characterize a 96-elementlibrary. Obviously, the total screening time will increase dramaticallyas the total number of elements increases. Therefore, it is desirable toprovide an apparatus and method for characterizing libraries ofdifferent materials using x-ray scattering to solve the above problemsassociated with conventional systems and techniques. It is to this endthat the present invention is directed.

SUMMARY OF THE INVENTION

An apparatus and method for characterizing a library of differentmaterials using x-ray scattering in accordance with the inventionprovides numerous advantages over conventional characterizationapparatus. For example, compared to conventional instruments, theapparatus advantageously delivers both a higher total photon flux and ahigher flux per unit area to each library element. This reduces the timerequired to analyze each element thereby reducing the total time neededfor library characterization. It also reduces the time required forcalibration of the instrument as described below. The light generated bysuch an intense beam when it strikes a phosphorescent screen is easilydetected by the eye which facilitates alignment of the instrument priorto the measurement. The apparatus also has a modular sample stage whichsupports and moves a library containing a plurality of elements so thatthe plurality of elements may be tested more rapidly than withconventional apparatus. The apparatus in accordance with the inventionmay perform spatial scanning so that arrays and libraries of materialsmay be rapidly analyzed and characterized. The positioning of thelibrary in relation to the x-ray beam may be computer controlled so thatthe apparatus may automatically characterize and analyze each element onthe library by moving the library a predetermined distance. Thisautomatic movement of the library relative to the x-ray beam eliminateshuman error and avoids having a human reposition the library after eachelement is characterized.

In accordance with another aspect of the invention, a method forpreparing a library of materials for characterization and analysis bythe x-ray apparatus is provided. The library may be prepared severaldifferent ways. In the embodiments below, samples which are powders arebeing used, but the library preparation method may be used with othertypes of samples. In a first embodiment, a plate having a predeterminedthickness may have an array of holes drilled through the plate. Theholes may be sealed at one end with a chemically inert material which isnearly transparent to x-rays of the appropriate wavelength and that doesnot generate appreciable x-ray scattering in the angular regime ofinterest. Suitable materials may include poly(imide) (Kapton™),poly(ethylene terephthalate) (Mylar™), thin aluminum foils and thinberyllium foils. Once the different materials have been deposited intothe appropriate hole, the open ends of the holes may be sealed with thesame material. The library is now ready for characterization using thex-ray apparatus. In a second embodiment, the same metal plate with afirst end covered by the plastic material may be used and then thepowders to be placed in each hole may be suspended in a non-solventliquid with a low vapor pressure and deposited in the appropriate holesusing a liquid handling robot. During the loading process, the plate maybe heated to promote evaporation of the non-solvent liquid and the otherend of the holes may be sealed with the same plastic which leaves thepowder in the hole for characterization. In a third embodiment, thesample powders may be blended with a viscous, non-solvent binder andeach sample may be deposited onto a piece of the plastic film. Once theelements are dried, the plastic film may be mounted on an aluminum frameto provide mechanical support and strength to the film which containsthe dried elements.

In a fourth embodiment of the library preparation method, the first endsof the holes in the same metal plate are blocked by a sheet of material,and the wells thus formed are filled by a solution of the materials ofinterest in a volatile solvent. The blocking material is chosen so as tobe nonreactive with respect to the solution of interest and to beinsoluble in the solvent. The blocking material may therefore includefluorinated polymers such as Teflon™, poly(imide) or metals. The solventis removed by air drying, by vacuum drying or by exposure to anoxygen-free environment followed by gentle heating in a vacuum. Once ofthe solvent has been removed, the remaining materials of interest mayform a film which completely fills and remains in each wells so that theblocking material may be removed. If the remaining materials of interestdo not form a film with sufficient mechanical strength to remain in thewells when the blocking material is removed, the blocking material mustbe made from a material that is substantially transparent to x-rays asdescribed above. Suitable materials may include poly(imide) (Kapton™,poly(ethylene terephthalate) (Mylar™), thin aluminum foils and thinberyllium foils.

Thus, in accordance with the invention, an apparatus for characterizinga library is provided in which the library contains an array ofelements, each element contains either a chemically distinctcombinations of materials, or a chemical composition which may beidentical to that existing elsewhere on the library but has been subjectto distinct processing conditions. The apparatus comprises an x-ray beamdirected at the library, a chamber which houses the library, and abeamline for directing the x-ray beam to illuminate a region on thelibrary in the chamber. The chamber further comprises a translationstage that holds the library and that is programmable to change theposition of the library relative to the x-ray beam and a controller thatcontrols the movement of the translation stage to expose each element tothe x-ray beam in order to rapidly characterize each element in thelibrary.

In accordance with another aspect of the invention, a method forcharacterizing a library is provided in which the library contains anarray of elements, each element contains either a chemically distinctcombinations of materials, or a chemical composition which may beidentical to that existing elsewhere on the library but has been subjectto distinct processing conditions. The method comprises directing anx-ray beam generated by an x-ray source towards the library housedwithin a chamber and moving the library in a predetermined manner toexpose each element of the library separately to the x-ray beam in orderto rapidly characterize each element in the library.

In accordance with another aspect of the invention, an apparatus forcharacterizing a library is provided in which the library contains anarray of elements and each element contains either a chemically distinctcombinations of materials, or a chemical composition which may beidentical to that existing elsewhere on the library but has been subjectto distinct processing conditions. The apparatus comprises means forgenerating an x-ray beam which is directed towards the library, achamber which houses the library and means for directing the x-ray beamonto the library in the chamber. The chamber further comprises means forholding the library, means for changing the position of the libraryrelative to the x-ray beam and means for controlling the movement of thetranslation stage to expose each element to the x-ray beam in order torapidly characterize each element in the library.

In accordance with yet another aspect of the invention, a method forpreparing a library is provided in which the library contains an arrayof elements and each element contains either a chemically distinctcombinations of materials, or a chemical composition which may beidentical to that existing elsewhere on the library but has been subjectto distinct processing conditions. The method comprises forming an arrayof holes from a first side of a plate through to a second side of theplate, sealing a first side of the plate with a film to form wells inthe plate, depositing a predetermined amount of one or more materialsinto each well of the plate, and sealing the second side of the platewith a second piece of film to trap the deposited one or materials ineach of the wells in the plate so that a beam may impinge upon eachelement containing the one or materials and characterize the elements ofthe library.

In accordance with yet another aspect of the invention, a method forpreparing a library is provided in which the library contains an arrayof elements and each element contains either a chemically distinctcombinations of materials, or a chemical composition which may beidentical to that existing elsewhere on the library but has been subjectto distinct processing conditions. The method comprises forming one ormore deposition compounds, each deposition compound comprising one ormore materials blended into a viscous, non-solvent liquid, depositingthe deposition compounds onto a sheet of film at predetermined locationsto form an array of elements, drying the deposition compounds onto thefilm to form a library of one or more materials, and mounting the firmwith the dried deposition compounds onto a frame to provide support tothe plastic film so that the deposition compounds may be rapidlycharacterized.

In accordance with still another aspect of the invention a method forpreparing a library is provided in which the library contains an arrayof elements and each element contains either a chemically distinctcombinations of materials, or a chemical composition which may beidentical to that existing elsewhere on the library but has been subjectto distinct processing conditions. The method comprises blocking thefirst ends of holes in a metal plate with a sheet of material so thatthe wells thus formed are filled by a solution of the materials ofinterest in a volatile solvent. The blocking material is chosen so as tobe nonreactive with respect to the solution of interest and to beinsoluble in the solvent. The solvent is then removed by air drying, byvacuum drying or by exposure to an oxygen-free environment followed bygentle heating in a vacuum. Once of the solvent has been removed, theremaining materials of interest may form a film which completely fillsand remains in each wells so that the blocking material may be removed.If the remaining materials of interest do not form a film withsufficient mechanical strength to remain in the wells when the blockingmaterial is removed, the blocking material must be made from a materialthat is substantially transparent to x-rays as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an x-ray characterizationapparatus in accordance with the invention;

FIG. 2A is a diagram illustrating more details of a transmission modex-ray characterization apparatus in accordance with the invention;

FIG. 2B is a diagram illustrating more details of a reflective modex-ray characterization apparatus in accordance with the invention;

FIG. 3 is a diagram illustrating an example of a library;

FIG. 4 is a side view of the translation stages in accordance with theinvention;

FIG. 5 is a top view of the translation stages shown in FIG. 4;

FIGS. 6 and 7 are diagrams illustrating the sealing plates which connectthe combinatorial sample chamber to the detector;

FIG. 8 is a block diagram illustrating more details of the libraryholder in accordance with the invention;

FIG. 9 is a flowchart illustrating a method for controlling the x-raycharacterization apparatus in accordance with the invention;

FIGS. 10A and B are diagrams illustrating a first and second embodimentsof a method for preparing a library in accordance with the invention;

FIG. 11 is a diagram illustrating a third embodiment of a method forpreparing a library in accordance with the invention;

FIG. 12 is a graph showing an example of the results obtained using thex-ray characterization apparatus to characterize block copolymers; and

FIG. 13 is a graph illustrating an example of the results obtained usingthe x-ray characterization apparatus to characterize a pigment library.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The invention is particularly applicable to an apparatus and method forcharacterizing a library of materials in powder form using x-rayscattering and it is in this context that the invention will bedescribed. It will be appreciated, however, that the apparatus andmethod in accordance with the invention has greater utility because itmay be used to characterize other materials.

An x-ray characterization apparatus and method in accordance with theinvention may provide various advantages over conventionalcharacterization apparatus. For example, the apparatus in accordancewith the invention significantly reduces the total amount of timetypically necessary to characterize a library of materials since theapparatus reduces the time needed to analyze each element of thelibrary. The apparatus also advantageously delivers more energy flux tothe surface of the library which reduces the time each element must beexposed to the x-ray beam. The apparatus also has a modular sample stagewhich supports and moves the library so that the elements of the librarymay be tested more rapidly than with a conventional apparatus. Theapparatus in accordance with the invention may perform spatial scanningso that arrays and libraries of materials may be rapidly analyzed andcharacterized. The positioning of the library in relation to the x-raybeam may be computer controlled so that the apparatus may automaticallycharacterize and analyze each element of the library by moving thelibrary a predetermined distance. This automatic movement of the libraryrelative to the x-ray beam eliminates human error and avoids having ahuman slowly re-position the library after each element ischaracterized. Now, an x-ray characterization apparatus in accordancewith the invention will be described.

FIG. 1 is a block diagram illustrating an x-ray characterization system12 in accordance with the invention which may include a computer system14 and an x-ray characterization apparatus 20. The computer system maybe a personal computer or any other type computer system. The computersystem 14 may control the operation of the x-ray characterizationapparatus 20 including the opening or closing of a servomechanicallycontrolled safety shutter as described below, the positioning of anelement in a library 46 as described below in front of an x-ray beam 15,receiving the scattering image data from the x-ray characterizationapparatus 20 and processing the scattered image data. The positioning ofthe library 46 and the reception and processing of the scattering imagedata may be performed by a software application 16 which may be storedin the computer system and executed by a microprocessor (not shown)contained in the computer system. The software application may be one ormore pieces of code. Thus, the software may, for example, automaticallyproperly position each element in the library in front of the x-ray beamso that each element may be characterized rapidly.

In operation, the x-ray characterization apparatus 20 generates an x-raybeam 15 which is directed by a beamline 17 towards an element of thelibrary 46. The x-ray beam is then scattered by the element which itstrikes. The individual photons scattered may be detected and a positionof each photons in a X-Y mesh of wires of a multiwire detector may bedetermined. The multiwire detector may be preferably used due to thehigh speed at which data may be transferred from the detector to thecomputer system. However, instead of the multiwire detector, other x-raydetectors known to those skilled in the art, such as a CCD detector orstorage phosphors (also known as image plates) may also be used todetect the scattered photons. The output of the detector for eachscattering may be sent to the computer system 14. Once thecharacterization of an element has been completed, the softwareapplication 16 may automatically move the library to expose anotherelement in the library 46 to the x-ray beam and generate scattering datafor that element. In this fashion, each element in the library isautomatically positioned in front of the x-ray beam 15 andcharacterized. Thus, the speed with which a library containing aplurality of elements may be characterized is greatly increased. Now,more details of the x-ray characterization apparatus 20, which mayinclude a transmission mode embodiment as shown in FIG. 2A and areflective mode embodiment shown in FIG. 2B, will be described.

FIG. 2A is a diagram illustrating an embodiment of the x-raycharacterization apparatus 20 in accordance with the invention. Thisembodiment is a transmission mode embodiment in which the generatedx-rays may pass through the elements in the library and the scatteredenergy may be recorded by a detector behind the library as describedbelow. The x-ray characterization apparatus 20 may include a source 22of intense x-ray radiation, an optional multi-layer mirror 24, a safetyshutter 26, a foil 28, a vertical focusing mirror 30, a horizontalfocusing mirror 32, a set of primary slits 34, a set of windows coatedwith a film 36, an optional first chamber 38, a set of parasitic slits40, a flight tube 42, a combinatorial sample chamber 44 in which alibrary 46 may be characterized using the intense x-ray beam, a beamstoptranslation assembly 48 and a x-ray ray detector 50. Each of theseelements of the x-ray characterization apparatus will now be describedin more detail.

The intense x-ray radiation source 22 may generate a beam of x-rayswhich are directed towards the library 46 in order to scatter the x-rayoff of (reflection mode) or through (transmissive mode) an element inthe library. In a preferred embodiment, the intense x-ray radiationsource 22 may be a rotating anode x-ray generator, such as a RigakuRU-200BH model, which may include a microfocus point focus cathode and acopper target. As is well known, an electron beam is generated bypassing an electric current through a tungsten filament and thenaccelerating the resulting free electrons through a potential differenceof 40 kV to produce 60 mA of beam current. The x-ray radiation may befocused to illuminate a predetermined spot size, such as 0.2×2 mm, onthe target surface, which may be foreshortened to 0.2×0.2 mm when viewedalong the beam axis. This generates a broad spectrum of x-rays comprisedof a number of discrete x-ray lines superimposed on a broad background.

In another embodiment of the invention, a synchrotron may be used as thesource of the intense x-ray radiation. Although synchrotron source arecapable of much higher photon fluxes and brilliances than can beobtained with laboratory sources (fixed anode or rotating anode x-raygenerators), such devices are considerably more complex and expensivethan laboratory sources. The high fluxes associated with a synchrotronalso places severe constraints on the performance of the associatedx-ray detectors, requiring detectors of greater cost and complexity aswell.

The radiation may exit the shielded enclosure of the source 22 through aberyllium window in the wall of the generator and may pass through awindow made of a material substantially transparent to x-rays, such asKapton™, into the multi-layer mirror 24. The multi-layer mirror is anoptional element which may be removed from the apparatus 20. The mirrormay be oriented so that it meets the Bragg criterion for the copper Kαwavelength (1.54 Å) which compose a majority of the total x-ray outputby the source 22 and the multi-layer thickness is varied along thelength of the mirror to convert the diverging radiation beam from thesource 22 into a parallel, nearly monochromatic beam. To minimizeabsorption or scattering of the x-ray radiation, the multi-layer mirrorchamber may be filled with helium gas. In a preferred embodiment, themulti-layer mirror may be a multi-layer mirror manufactured by OsmicCorp. of Troy, Mich.

To avoid accidents, the x-ray generator 22 may have a servomechanicallyactuated lead shutter immediately after the beryllium window whichblocks the beam when it is not use. To provide further backup to theshutter in the generator 22, the apparatus may include a mechanicalshutter 26. The output from the shutter, if open, is then passed throughthe foil 28. The material of the foil may be selected to exhibitpreferential absorption for photons with energies higher than a desiredenergy which further monochromaticizes the beam. For the copper Kαradiation being used, the foil may be made out of nickel. If other x-raytarget materials such as molybdenum are used, then a different foilmaterial may be used.

Once the beam passes through the foil, it strikes the vertical focusingmirror 30 and the horizontal focusing mirror 32, each of which may be awell-known Franks mirror. The focusing mirrors 30, 32 may be a grazingincident mirror constructed from two float glass flats coated with athin layer of nickel and oriented so as to reflect x-rays withwavelengths equal to or greater than the Kα wavelength. Thus, higherenergy photons pass through both of the mirrors. The mirrors, by meansof a bending press, may each be curved so as to focus the parallel beamfrom the multi-layer mirror 24 to a point at the location of thedetector 50. To minimize unwanted absorption and scattering of the x-raybeams, the vertical and horizontal focusing mirrors 30, 32 may bemaintained in a helium atmosphere.

Once the beam passes through the vertical and horizontal focusingmirrors 30, 32, the beam passes through the set of primary slits 34which helps to determine the exact dimensions of the beam striking theelements on the library and to block unwanted unreflected radiationwhich may be present. At this point, the x-ray beam exits the opticalbeam line which is helium filled, as described above, through the set ofwindows 36 made from a nearly transparent material, such as Kapton™, forexample, into the optional first chamber 38 which may have a vacuumapplied to it. In this apparatus, the first chamber is not used for asample since this chamber can only contain a single sample. Therefore,instead of the first chamber 38, a flight tube may replace the firstchamber. If the first chamber is used, the beam may strike a set ofparasitic slits 40, located about 10 cm downstream from the set ofprimary slits 34, which eliminate any parasitic scattering caused by theset of primary slits. When the flight tube is used instead, theparasitic slits may be mounted at the end of the flight tube.

For the characterization measurements in accordance with the invention,the flight tube 42 may be attached to the first chamber if the firstchamber is used. The flight tube may be a predetermined length, such as50 cm, which is chosen such that radiation scattered through theangle(s) of interest strikes the detector with sufficient lateralseparation from the transmitted radiation so as to distinguish betweentransmitted photons and scattered photons. The angles are dictated bythe wavelength of the incident x-rays and the dimensions of thescattering features within the sample. The flight tube may bemanufactured out of aluminum and may have a vacuum applied. The flighttube may serve as an evacuated beampath for the transmitted andscattered radiation when the first chamber 38 is being used forcharacterizing a single sample. The back end of the flight tube 42 maybe connected to the combinatorial sample chamber 44 to form a continuousevacuated beampath.

As the intense x-ray beam passes through the combinatorial samplechamber 44, the beam passes through or reflects off of an element in thelibrary positioned in front of the beam, as described below. Thetransmitted, scattered and reflected radiation exits the combinatorialsample chamber 44. In the transmissive embodiment of the invention, theradiation transmitted through the element may be blocked by the beamstoptranslation assembly 48 which may be a lead disk mounted on a strip ofmaterial, such as Mylar™. The material is attached to a two-axistranslation system which permits the location of the beamstop to beadjusted (i.e., behind the element currently being characterized) whilethe combinatorial sample chamber 44 is kept evacuated. The radiationscattered off of the element in the library may then be detected by thedetector 50. In a preferred embodiment, the detector 50 may be SeimensHI-STAR multiwire area detector. Now, the combinatorial sample chamber44 will be described in more detail with additional details beingprovided below.

The combinatorial sample chamber 44 may be attached to an optical railon which the detector is also placed so that the position of the library46 in the combinatorial sample chamber 44 relative to the detector 50may be adjusted. In particular, for elements with small features andtherefore large scattering angles, the library may be closer to thedetector (approximately 1-4 cm), while for a element with largerfeatures and therefore smaller scattering angles, the library may be 1-2m from the detector.

The combinatorial sample chamber 44 may permit a variety of differentenvironmental characteristics to be changed so that the effects ofchanges in the environmental characteristics on the elements may bemeasured. For example, the combinatorial sample chamber 44 may bepressurized to a positive pressure or a vacuum to determine, forexample, the effects of a determined time at a particular pressure onthe library or even on a particular element. In this case, additionalpressure-tight nearly transparent windows may be mounted at theapertures where the x-rays enter and exit the chamber 44. As anotherexample, an electric or magnetic field may be applied to one or moreelements in the library as described in co-pending U.S. patentapplication Ser. No. 09/174,986, filed Oct. 19, 1998 on behalf of thesame assignee as this patent and which is incorporated herein byreference. In addition, some form of mechanical stress, such as shearstress or stretching stress, may be applied to the library. Thetemperature or the gases within the combinatorial sample chamber 44 mayalso be changed to determine the effects of different temperature orgases on the elements. Finally, to look at the thermal changes of aelement, such as a catalyst, each element in the library may include anembedded thermal sensor and heater.

Within the combinatorial sample chamber 44, there may be twoorthogonally mounted linear translation stages, as described below. Aframe attached to one of the translation stages, as described below, mayaccept a library containing a plurality of elements or elements, such asninety-six elements in a preferred embodiment. The samples or elementsmay be powders, solutions, suspensions or films deposited or transparentsubstrates as will be described below with reference to FIGS. 11 and 12.In the transmissive embodiment shown in FIG. 2, the frame is oriented bythe translation stages to be normal to the x-ray beam so that somefraction of the incident photons are scattered our of the main beam asit passes through the library element. To position the stages, a pair ofcomputer-controlled motors, such as stepper motors, may be used asdescribed below. The stepper motors may be controlled by the softwareapplication 16 shown in FIG. 1. In one embodiment of the invention,closed-loop motor control may be used. In another embodiment, noclosed-loop motor control is used so that the software application 16directs each motor to step an appropriate number of times in the desireddirection to obtain the desired displacement from the starting point toa particular point at which a particular element is in front of thex-ray beam.

To calibrate the x-ray characterization apparatus 20 to characterizeelements of the library, a radioactive source may be installed on theframe which normally holds the library at the proper spatial location sothe focused x-ray beam passes through the radioactive source. Thecharacteristics of the detector are then determined as specified bywell-known procedures. Next, the radioactive source is removed and asecond frame containing a calibrant powder is installed. The calibrantpowder may be supplied by the National Institute of Standards andTechnology (NIST) and may be lanthanum hexaborate (d=4.157 Å). Thescattering from this calibrant powder may be used to determine thelibrary-to-detector distance needed for subsequent measurements.

During the characterization of each element in a library, the variouscommands needed to acquire and process the data for each element in thelibrary may be written into a text file which may be read by thedetector as is well known. Once a library is inserted into the frame,the translation stages may be moved so that the x-ray beam passesthrough a first element. The x-ray safety shutter may then be opened andthe first scattering image is recorded. The translation stage controlsoftware may then move the library to bring the next element of thelibrary into the path of the x-ray beam. After recording the secondimage, the library is moved to the next element. While the library isbeing moved, which takes several seconds, the detector may process andsave the image. The computer controlling the detector and the computersoftware controlling the motors may or may not communicate with eachother. If the software application do communicate with each other, thenthe next exposure may proceed as soon as the library is properlypositioned. In this manner, each element in the library may becharacterized.

During the processing of the scattering data, which may occur in thedetector or in the computer system, various operation may occur. Forexample, the raw scattering data may be corrected for detector responsecharacteristics, such as spatial distortion or non-uniform sensitivity.This correction may be followed by a determination of the total numberof counter (crossings of the detector wires) as a function of scatteringangle (2θ) over a fixed range of azimuthal angles (χ). Now, a reflectivemode embodiment of the x-ray characterization apparatus 20 in accordancewith the invention will be described.

FIG. 2B is a diagram illustrating a reflective mode embodiment of thex-ray characterization apparatus 20 in accordance with the invention.For the description of this embodiment, many parts are similar to thetransmission mode apparatus described above and these parts will not bedescribed here in any detail. Thus, the reflective mode apparatus 20 mayinclude the intense x-ray source 22, the optional multi-layer mirror 24,the safety shutter 26, the foil 28, the first and second sets offocusing mirrors 30, 32, the primary slits 34, the window 36, the flighttube 42 and the set of parasitic slits 40. In this embodiment, however,one end of the flight tube 42 is connected to the second set of focusingmirrors 32 and the parasitic slits 40 are connected to the other end ofthe flight tube 42 since the library 46 and the combinatorial samplechamber 44 are now separate from the rest of a beamline so that thebeamline and the detector 50 may rotate relative to the library 46 aswill be described below. In particular, for the reflective embodiment ofthe apparatus, a beamline 52 and a detector assembly 54 may be rotatedabout a fixed combinatorial sample chamber 44. Therefore, the beamline52 and the detector assembly 54 may each be connected to a typicalrotation stage arm (not shown) to permit the beamline 52 and detectorassembly 54 to be rotated relative to the library 46. Thus, thepositions of the beamline and detector may be adjusted to the properreflection angle to detect the x-rays reflected off of the library.

The beamline 52 has the same elements as described above and performsthe same function of generating an intense focused x-ray beam anddirecting it towards the library 46. The detector assembly 54 in thisembodiment may include the beamstop assembly 48, the detector 50, aflight tube 55 and a window 56 through which the scattered x-ray beamsmay enter the detector assembly. In this embodiment, there may be analternate combinatorial sample chamber 57 which may be used for largescattering angles. The alternate combinatorial sample chamber 57 mayinclude a window 58 through which the x-rays may pass. The combinatorialsample chamber 44 may have a cylindrical shape and may be filled withhelium gas to reduce unwanted scattering. As above, the combinatorialsample chamber 44 may have a mechanism, as described below withreference to FIGS. 4 and 5, to position the library in the properposition. As above, the positioning of the library may be computercontrolled. Now, an example of a library will be described.

FIG. 3 is a diagram illustrating an example of a library 60. The librarymay be mounted onto the frame to characterize each element in thelibrary. The library may comprise a plate 62, which may be made of ametallic material such as aluminum, having a predetermined thickness,such as ⅛″, and a plurality of holes 64 through the plate in apredetermined pattern. In this example, the holes may be drilled throughthe plate, may be in a rectangular, two-dimensional array pattern, andthere may be a total of ninety-six elements in the library. For eachhole in the plate, there may be a sample deposited within and sealedinto the hole so that the x-ray beam may characterize thecharacteristics of the sample. The library 60 in accordance with theinvention may have other shapes and more or less elements than shown inFIG. 3. Several different embodiments for preparing a library inaccordance with the invention will be described below with reference toFIGS. 10A, 10B and 11. Now, more details of the translation stages inaccordance with the invention will be described.

FIGS. 4 and 5 are a side view and top view, respectively, of translationstages located within the combinatorial sample chamber 44 in accordancewith the invention. As shown in FIG. 5, within the combinatorial samplechamber 44 may be a library holder assembly 70 which positions thelibrary 46 relative to the x-ray beam entering the combinatorial samplechamber 44 from the flight tube 42. The combinatorial sample chamber 44may be attached to the detector 50 which detects the scattering of thex-rays off of the elements in the elements of the library. The positionof the detector 50 may be adjusted relative to the position of thelibrary as described below.

The library holder assembly 70, as shown in FIG. 4, may include a pairof rails 72 which hold the library 46. The rails 72 may be attached to afirst positioning assembly 74. The first positioning assembly 74 maypermit the library to move back and forth along a first axis 75 using amotor 76, such as a stepper motor, which may be controlled by thesoftware application being executed by the computer system as shown inFIG. 1. The first positioning assembly 74 may be connected to a secondpositioning assembly 78 which may include a stepper motor 80 which movesthe library back and forth along a second axis 82. The secondpositioning assembly 78 may also be controlled by the softwareapplication being executed by the computer system as shown in FIG. 1.Thus, using the computer controlled first and second positioningassemblies 74, 78, the library 46 may be automatically positioned sothat each element of the library may be characterized using the x-raybeam which increases the speed with which the library may becharacterized. The order in which the elements of the library areactually analyzed is not critical to the invention. The library holderassembly 70 may also include a system 84 for rotating the library, and afirst and second manual positioning assemblies 86, 88, such aslaboratory jacks, for positioning the combinatorial sample chamberduring initial installation and calibration.

To adjust the position of the detector 50 relative to the library 46,the detector may be mounted on a sliding plate mechanism 90. As shown inFIGS. 6 and 7, the sliding plate mechanism 90 may include a seal 92,such as an O-ring, on the outer surface of the combinatorial samplechamber 44 and a sealing plate 94 attached to the face of the detector.The sealing plate 94 may include a seal 96, such as an O-ring, whichseals the sealing plate 94 to the detector 50. Thus, the detector 50 andthe sealing plate 94 may be moved relative to the combinatorial samplechamber 44 and the seal 92 along a direction τ. When the detector 50 isproperly positioned, the sealing plate 94 may be clamped to the wall ofthe combinatorial sample chamber 44 so that the seal 92 forms anair-tight seal between the combinatorial sample chamber 44, the detectorand the sealing plate. Now, the details of an embodiment of the rails 72which hold the library will be described briefly.

FIG. 8 is a block diagram illustrating an embodiment of the rails 72which hold the library. In this embodiment, the rails 72 may include afirst rail 100 with a channel 102 at its center and a second rail 104with a channel 106 at its center so that a library may slide between therails 100, 104 in the channels 102, 106 and be supported by the railsduring the characterization of the elements in the library. Now, themethod for controlling the x-ray characterization apparatus will bedescribed.

FIG. 9 is a flowchart illustrating a method 110 for controlling thex-ray characterization apparatus in accordance with the invention torapidly characterize each element in a library. In step 112, the x-rayapparatus may be calibrated as described above. Once the apparatus iscalibrated, a library may be inserted into the rails of the libraryholder mechanism in step 114. At this point, the first and secondpositioning assemblies are activated in order to move the library to theposition as commanded by the software application executed on thecomputer system in order to characterize each element in the libraryrapidly. Thus, in step 116, the first and second positioning assembliesare commanded to take a certain predetermined number of steps to placethe library in an initial position in which a first element of thelibrary is aligned with the x-ray beam. Next, in step 117, the countersassociated with the motors are zeroed since this embodiment of theinvention does not use closed loop feedback so that each movement of themotors is from an origin which is set to the initial element of thelibrary. Once the library is positioned in the first position, thesafety shutter may be removed and the scattering image generated in step118 when the x-ray beam passes through the first element is recorded bythe detector. For most libraries, this first element may be acalibration element. Once the image for the first element is processedand recorded, the software application commands the stepper motors inthe first and second positioning assemblies to step a predeterminednumber of steps, in step 120, to position the library so that the nextelement in the library may be characterized. In accordance with anotherembodiment of the invention in which only selected elements of thelibrary may be characterized, a list of elements and their positions maybe provided to the motor controller which then moves the library to theappropriate locations to expose the selected library elements. In oneembodiment of the invention, which does not use closed loop feedbacktechniques, each motor is commanded to step a predetermined number oftimes from the origin to position the library properly based oninformation about the library and the position of each element in thelibrary previously generated and available to the software application.The invention may also operate with a closed loop feedback system inwhich the motors may be commanded to perform a predetermined number ofsteps and then any error in the positioning may be corrected.

Once the library has been positioned so that next element may be exposedto the x-ray beam, the element is exposed to the x-ray beam in step 122and an image of the scattering is generated by the detector. In step124, the detector may process the image as described above and store theimage in a memory which may be in the computer system or in thedetector. While the detector is processing the image, the softwareapplication may determine if there is another element to becharacterized in step 126, and loop back to step 120 and command thestepper motors to move the library so that the next element is exposedto the x-ray beam. In this manner, the processing of the image by thedetector and the movement of the first and second positioning assembliesto a next element may occur simultaneously which reduces the total timeto characterize each element in the library. In one embodiment of theinvention, the detector does not communicate with the softwareapplication so that the total time to characterize each element islimited to the slowest step (i.e., either the processing or the movementof the stepper motors). In another embodiment of the invention, thedetector and software application may communicate with each other sothat, as soon as the processing of the image and the movement of thestepper motors is completed, the next element may be characterized whichmay further reduce the total time necessary to characterize each elementin the library. When each element in the library has been characterizedthe method has been completed.

In addition to serially characterizing each element in a library, thex-ray apparatus may also be controlled by the software application sothat the user of the x-ray apparatus may select to characterize anyindividual element, a group of elements, etc. of the library by simplyspecifying the library element(s) to be characterized using a simpleuser interface screen which permits the user to select one or moreelements in the library from a graphical representation of the library.For example, once the particular elements are specified by the user, thesoftware application may automatically determine the appropriate numberof steps for the first and second positioning assemblies to take inorder to position the library to bring the selected element into thex-ray beam. In this manner, the user of the apparatus may determine theelements of interest in the library and the apparatus automaticallypositions the library which greatly increases the speed with which thecharacterization of element(s) in the library may occur. The softwarealso permits individual elements of the library to be independentlyaddressable. Now, another embodiment of the characterization method inwhich the detector computer running the software that controls thedetector and the motor controller computer running the software whichcontrols the motors that move the library are separate computer systemswill be described in which more details of the method are provided.

In the embodiment of the invention where the detector computer and themotor controller computer are separate, the general steps performed aresimilar, but the details are different since the two computer systems donot communicate with each other. Thus, in this embodiment, afterrecording all of the detector correction files as specified by thedetector manufacturer and calibrating the sample-to-detector distance,the library is placed in the library holder, and positioned so that thex-ray beam passes through the upper left element of the library(typically denoted by A1). The library position counters may then bezeroed, as described above, to indicate to the motor controller computerthat the library is positioned in the initial position. Using a userinterface at the motor controller computer, the user may specify thelibrary elements to be analyzed, the exposure time to be used for eachelement, and the manner in-which the two-dimensional images are to bereduced to a one-dimensional profile of counts as a function ofposition. The motor controller may then generate a list of the positionof each element(s) chosen, and a script (e.g., a list of instructions)which is transferred to the detector computer.

The data collection begins when the detector computer is directed tostart reading commands from the script. At the same time, the motorcomputer software is placed into a program mode which locks out manualcontrol of the motor position. In this mode, the motor computer waitsfor a signal from the detector computer to step to the next element inthe position list. Once that signal is received, the motor computersteps the horizontal and vertical motors to the appropriate amount tobring the next element into the x-ray beam.

For each element, the detector computer integrates the photons receivedby the x-ray detector for a preset time period. Once the imagecollection is complete, the detector computer signals the motor computerto move to the next element. While the motor computer is executing thistranslation of the library, the next image is corrected for detectorresponse characteristics, written to a hard disk and collapsed into aone-dimensional format which is also written to disk. The detectorassumes that the translation of the library is complete at this point(which is appropriate due to the motor's rate of speed) and immediatelystarts acquiring the next image. Once the motor computer steps to thelast element in the position list, it returns to “normal” mode in whichthe motors may be operated by the user.

In the preferred embodiment described with reference to FIG. 9, thedetector computer and the motor controller computer are preferably onecomputer system running a software application to handle the detectorcontrol and running another software application which controls themotors so that the two processes may communicate with each other. Inaddition, in the preferred embodiment, the detector controller and themotor controller may signal each other so that the motor controller mayindicate to the detector controller that the library is appropriatelypositioned so that the next image may be generated and stored by thedetector.

Thus, in accordance with the invention, an entire library, a portion ofa library or a single element in the library may be rapidly positionedand characterized. With a conventional characterization apparatus, anelement in a ninety-six element library may require approximately 15minutes to characterize while the characterization of the entire librarymay require at least 24 hours to complete. With the x-ray apparatus inaccordance with the invention, however, each element may takeapproximately 3 minutes to characterize so that the entire library maybe characterized in approximately 2.5 hours. The increase in thecharacterization speed of the library is due to several factors.

First, the x-ray source in accordance with the invention generates anx-ray beam which is more intense (directs more flux to the library) thanthe conventional x-ray apparatus. The greater intensity x-rays means areduced exposure time for each library element. A conventional x-rayapparatus and associated optics typically generate a beam containing onthe order of 10,000 photons per second while the x-ray apparatus inaccordance with the invention may generate at least 6 million photonsper second. The intensity of the x-ray beam is increased due to astronger x-ray source and a better beamline which reduces unwantedscattering and ensures the focused x-ray beam arrives at the library.

The increase in the characterization speed of the x-ray apparatus inaccordance with the invention is also due to the first and secondpositioning assemblies in combination with the software applicationwhich permit the library to be rapidly and automatically positioned tocharacterize each element of the library rapidly. Now, severalembodiments of methods for preparing a library that may be used with thex-ray apparatus will be described.

FIGS. 10A and 10B are diagrams illustrating first and second embodimentsof a method for preparing a library in accordance with the invention. Asshown in FIG. 10A, a library 129 may include a plate 130, which may bemanufactured out of a material sufficiently strong to support thelibrary. For example, the plate may be made from a metallic materialsuch as aluminum. The plate may have a predetermined pattern of holes132 formed through the plate. The holes may be formed, for example, bydrilling the holes through the plate. In the example shown, arectangular array of holes is shown. Once the holes are formed, a pieceof adhesive tape or film 134 may be attached to the back surface of theplate as shown by the arrow in FIG. 10A to form a predetermined patternof wells into which samples 135 may be deposited so that the elementsmay be characterized. The film 134 may be translucent and/or may permitthe x-ray which impinge upon the sample in the well to pass through thefilm. In a preferred embodiment of the invention, the adhesive film maybe Kapton™.

In one embodiment, once dry samples 135 have been manually orautomatically deposited in each well, a second film 136, as shown inFIG. 10B, may be placed on top of the plate 130 to seal the samples intotheir individual wells in the plate. The second piece of adhesivefilm/tape may be translucent and/or may permit the x-rays which impingeupon the sample in the well to pass through the film and may preferablybe Kapton™. The prepared library 129 in accordance with this embodimentof the invention is shown in FIG. 10B.

In accordance with a second embodiment of the invention, each sample maybe mixed with a non-solvent liquid and then the combination of theliquid and dry sample may be deposited in each well of the library usinga liquid dispensing robot. Prior to the second film 136 being applied tothe plate to seal the samples, the plate and sampled may be heated toevaporate the liquid. Once the liquid is evaporated, the second film maybe applied to the plate. The end result of this second embodiment is thesame library shown in FIG. 10B. Now, a third embodiment of the methodfor preparing a library will be described.

FIG. 11 is a diagram illustrating a third embodiment of a method forpreparing a library 129 in accordance with the invention. In thisembodiment, a film 138, which may be translucent and/or permit x-rays topass through the adhesive film, such as Kapton™, may be used as a basefor the preparation of the library. In particular, a plurality ofsamples 140 to be included in the library may be mixed with anon-solvent liquid and then deposited on the film in a predeterminedpattern similar to the pattern formed by the holes in the plate in theabove embodiments. The samples may be deposited by typical semiconductordeposition techniques. Once the deposited samples are dried, a frame 142may be attached to the side of the film opposite of the samples tosupport the film and elements during characterization by the x-ray beam.In accordance with all of these embodiments, a library 129 is preparedwhich may be inserted into the x-ray characterization apparatus inaccordance with the invention. Now, an example showing the preparationof a pigment library will be briefly described.

To prepare a library containing pigments, the pigment samples aresynthesized on commercially available polypropylene filter plates. Afterthe synthesis is complete and the library is dried, the solid at thebottom of each well is crushed using a 96-pin tool for a 96 elementlibrary. Once the samples are crushed, a 96-well aluminum plate, whichhas a film attached to its back surface, may be placed on top of thefilter plate. The assembly may then be inverted and shaken to load thelibrary contents into the wells in the aluminum plate. The aluminumplate may then be covered with an adhesive tape, such as Kapton™, toseal the contents into each well in the aluminum plate. The preparationof the pigment library has now been completed.

In addition to the embodiments of the x-ray apparatus described above,the x-ray apparatus may also use a well known synchrotron to generatethe intense x-rays. When using the synchrotron, a more intense x-raybeam is generated so that the exposure time for each element in thelibrary is further reduced to about 1-2 seconds per element. To capturethe scattered x-rays generated by the synchrotron, however, a typicalmultiwire detector used in the prior embodiments is too slow so that aspecialized multiwire detector, or an integrating detector, such as acharge coupled device (CCD), may be used. Now, two examples of theresults obtained using the x-ray characterization apparatus will bedescribed.

FIG. 12 is a graph 150 showing an example of the results obtained usingthe x-ray characterization apparatus to characterize block copolymers.In particular, the data in the graph is recorded from a film ofcommercially available poly(styrene)-poly(butadiene) block copolymerobtained from Aldrich Chemical Co. (catalog number 43,249-0) containing30% by weight styrene and characterized as received. A 0.125″ thickaluminum sample plate containing 96{fraction (3/32)}″ diameter holesarranged in an 8×12 array was used for this measurement. One face of theplate was compressed against a Teflon™ substrate such that one end ofthe holes was blocked which formed wells in the plate. Each well wasinitially filled with approximately 50 ul of a concentrated solution(approximately 25% by weight) of this polymer in toluene. The plate wasthen dried in a fume hood at ambient temperature, pressure and oxygencontent for approximately one hour. 20 ul of the concentrated polymersolution was then added to each well and the drying process wasrepeated. This process was repeated until each well was filled with thesolid polymer.

Any residual solvent was then removed by drying the plate and theTeflon™ backing in a vacuum atmosphere for 24 hours at room temperature,followed by a slow heating to 135 C and subsequent annealing in vacuumat that temperature for 48 hours. At this point, after slow cooling toroom temperature, the plate was returned to atmospheric pressure and theTeflon™ backing was removed. For these samples, an x-ray exposureminimum time of 10 seconds at rotating anode power settings of 40 kVaccelerating voltage and 60 mA of beam current was used. An exposuretime of 300 seconds was used in the representative image, recorded fromelement A5 of the plate, in order to obtain higher order diffractiondata. The reflections appear at angular position ratios of 1:2:4:5 whichis characteristic of the alternating layers of polystyrene andpolybutadiene. Although no sample-to-detector calibration was recordedfor these data, prior calibration indicates that this distance isapproximately 205 cm. Assuming this value leads to the to angular valuesshown on the x-axis; the peak positions the correspond to an interlayerspacing of approximately 40 nm. Now, a second example of the resultsobtained using the x-ray characterization apparatus to characterize apigment library will be described.

FIG. 13 is a graph 160 illustrating an example of the results obtainedusing the x-ray characterization apparatus to characterize a library ofpigment powders. The library was prepared by the preparation methodoutlined above. An integration time of 60 seconds was used for eachelement in the library and the sample-to-detector distance wascalibrated using the known spacing of lanthanum hexaborate prior to themeasurement. In the graph, three traces are shown, one for a solidsolution of two pigments, and one for each of the component pigments (Aand B). The scattering of the solid solution, based on the resultsdisplayed in the graph, is not given by a linear combination of thescatterings for the two components since the former exhibits severalpeaks (at 6.8, 24.1, 31.0 and 32.3 degrees) that do not appear in thetraces for either component.

While the foregoing has been with reference to a particular embodimentof the invention, it will be appreciated by those skilled in the artthat changes in this embodiment may be made without departing from theprinciples and spirit of the invention, the scope of which is defined bythe appended claims.

What is claimed is:
 1. An apparatus for characterizing a library, thelibrary containing an array of members elements, at least a plurality ofthe members in the array containing a different combination ofmaterials, the apparatus comprising: an x-ray beam source which directsx-rays towards the library; a chamber which houses the library; abeamline for directing the x-ray beam onto the library in the chamber;the chamber further comprising a translation stage that holds thelibrary and that is programmable to change the position of the libraryrelative to the x-ray beam and a controller that controls the movementof the translation stage to expose an element to the x-ray beam in orderto rapidly characterize the member in the library, the x-ray beamscattering off of the member; and a detector which detects the scatteredx-ray beam in order to generate characterization data for the member. 2.The apparatus of claim 1, wherein the translation stage comprises afirst positioning mechanism for positioning the library along a firstaxis and a second positioning mechanism for positioning the libraryalong a second axis.
 3. The apparatus of claim 2, wherein the first andsecond positioning mechanisms comprise a stepper motor.
 4. The apparatusof claim 1, wherein the controller further comprises a computer systemhaving a user interface so that each member of the library isindependently selectable by the user.
 5. The apparatus of claim 1,wherein the detector and the beamline are mounted onto a rotation stageso that the positions of the detector and beamline are adjustable basedon the reflective scattering angle of the x-ray beam off of the elementin the library.
 6. The apparatus of claim 1, wherein the x-ray beamsource comprises a rotating anode x-ray generator.
 7. The apparatus ofclaim 1, wherein the x-ray beam source comprises a synchrotron.
 8. Theapparatus of claim 1, wherein the x-ray beam source comprises astationary target x-ray generator.
 9. The apparatus of claim 1, whereinsaid plurality of members comprises at least 10 members.
 10. Theapparatus of claim 1, wherein said plurality of members comprises atleast 25 members.
 11. The apparatus of claim 1, wherein said pluralityof members comprises at least 50 members.
 12. The apparatus of claim 1,wherein said plurality of members comprises at least 100 members.
 13. Amethod for characterizing a library, the library containing an array ofmembers, at least a plurality of the members containing a differentcombination of materials, the method comprising: directing an x-ray beamgenerated by an x-ray source towards the library housed within achamber; directing the x-ray beam onto the library in the chamber;moving the library in a predetermined manner to expose a member of thelibrary to the x-ray beam in order to rapidly characterize each memberin the library, the x-ray beam scattering off of the member; anddetecting the scattered x-ray beam in order to characterize the member.14. The method of claim 13, wherein moving the library comprisespositioning the library along a first axis and positioning the libraryalong a second axis.
 15. The method of claim 13 further comprisingselecting, based on user input, one or more members of the library to becharacterized and automatically moving the library to expose the one ormore selected elements of the library to the x-ray beam in order tocharacterize the one or more selected elements.
 16. The method of claim13, wherein said plurality of members comprises at least 10 members. 17.The method of claim 13, wherein said plurality of members comprises atleast 25 members.
 18. The method of claim 13, wherein said plurality ofmembers comprises at least 50 members.
 19. The method of claim 13,wherein said plurality of members comprises at least 100 members.
 20. Anapparatus for characterizing a library, the library containing an arrayof members, at least a plurality of members containing a differentcombination of materials, the apparatus comprising: means for generatingan x-ray beam which is directed towards the library; a chamber whichhouses the library; means for directing the x-ray beam onto the libraryin the chamber; the chamber further comprising means for holding thelibrary, means for changing the position of the library relative to thex-ray beam to expose a member to the x-ray beam in order to rapidlycharacterize the member, the x-ray beam scattering off of the member;and means for detecting the scattered x-ray beam in order tocharacterize the member.
 21. The apparatus of claim 20 wherein theposition changing means comprises means for positioning the libraryalong a first axis and means for positioning the library along a secondaxis.
 22. The apparatus of claim 20 wherein the first and secondpositioning means comprise a stepper motor.
 23. The apparatus of claim20 wherein the positioning changing means comprises means for selectingone or more of the elements of the library to be characterized and meansfor positioning the library to expose the one or more selected elementsto be x-ray beam to characterize the one or more selected elements. 24.The apparatus of claim 20 wherein the detector means and the directingmeans are mounted onto a rotation stage so that the positions of thedetector and beamline are adjustable based on the reflective scatteringangle of the x-ray beam off of the element in the library.